1. Field of the Invention
The present invention relates to an apparatus having a refrigeration circuit using difluoromethane as a refrigerant.
2. Detailed Description of the Related Art
Conventionally, chlorodifluoromethane (R22, boiling point: xe2x88x9240.8xc2x0 C.) has been used as a refrigerant for an apparatus having a refrigeration circuit. R22 is however potentially highly destructive to ozone. R22 discharged into the atmosphere and reaching the ozone layer in the upper atmosphere destroys this ozone layer. Therefore, R22 has been under CFC restriction.
The destruction of the ozone layer is caused by chlorine (Cl) included in the refrigerant. Therefore, a refrigerant free from chlorine such as difluoromethane (referred to as HFC-32 or R32, boiling point: xe2x88x9252xc2x0 C.) is considered as a substitute refrigerant for R22 for its relatively small global warming potential (GWP) and high efficiency (with COP increased by about 10%).
As a result, there has been a demand for development of an apparatus having a refrigeration circuit using difluoromethane. Above all, development of a highly reliable, high performance compressor adapted to the use of difluoromethane has been awaited.
Meanwhile, compressors are divided into reciprocating type and rotating type compressors. The reciprocating type compressor suffers from noise or vibration disadvantages. Therefore, there has been a demand for a rotating type compressor using difluoromethane.
However, when difluoromethane is compressed using the rotating type compressor, the temperature of the compressed difluoromethane could be higher than the temperature of other conventional refrigerants. As a result, the chemical stability of the lubricating oil or the difluoromethane itself is lowered, which disadvantageously lowers the performance and reliability of the apparatus having a refrigeration circuit as a whole.
The present invention is directed to a solution to this problem, and it is an object of the present invention to provide an apparatus having are frigeration circuit with high reliability and performance by which the chemical stability of the lubricating oil or difluoromethane used as a refrigerant is not impaired.
According to the present invention, there is provided an apparatus having a refrigeration circuit including a rotary compressor having a rotary roller, and a vane forming a compression space inside by abutting against the roller, the compressor storing in an enclosed container a rotary compressing element provided with a plurality of cylinders having both opening ends closed and compressing an inhaled refrigerant in a plurality of stages by the compressing element for discharging; a condenser; an expansion valve and a cooler, where difluoromethane is used as the refrigerant.
Here, the apparatus having a refrigeration circuit according to a first aspect of the invention includes a first cooler provided in a refrigerant flow path between the cylinders of the rotary compression element for cooling the difluoromethane to be compressed in the plurality of stages.
According to the first aspect of the present invention, the first cooler lowers the temperature of the difluoromethane as a refrigerant inhaled/discharged to/from the rotary compressor, so that the chemical stability of the lubricating oil or difluoromethane is not impaired and that the performance and reliability of the apparatus having a refrigeration circuit may be improved.
The apparatus having a refrigeration circuit according to a second aspect of the present invention has a second cooler provided in the refrigeration circuit for cooling difluoromethane.
According to the second aspect of the present invention, the second cooler lowers the temperature of the difluoromethane as a refrigerant inhaled/discharged to/from the rotary compressor, so that the chemical stability of the lubricating oil or difluoromethane is not impaired and that the performance and reliability of the apparatus having a refrigeration circuit may be improved.
The apparatus having a refrigeration circuit according to a third aspect of the present invention includes a first cooler provided in the refrigerant flow path between the cylinders of the rotary compression elements for cooling difluoromethane to be compressed in a plurality of stages, and a second cooler provided in the refrigeration circuit for cooling difluoromethane.
According to the third aspect of the invention, the first cooler and the second cooler further lower the temperature of difluoromethane as a refrigerant inhaled/discharged to/from the rotary compressor, so that the chemical stability of lubricating oil or the difluoromethane is not impaired and that the performance and reliability of the apparatus having a refrigeration circuit may be even more improved.